1. Field of the Invention
The present invention relates to an iron type golf club head and, more particularly, to a golf club head in which traces are formed on the face by milling.
2. Description of the Related Art
U.S. Pat. No. 5,437,088 describes a golf club head in which traces (cutting marks) are formed on the face by milling (cutting by a milling machine). According to this patent, after forming corrugations (scoring lines) on the face, the face undergoes milling to sharpen the edges of the corrugations. The sharp edges and traces formed by milling increase the spin of the ball. FIG. 1a of this patent shows that the pitch of the corrugations is almost equal to that of the traces. As the traces, both downwardly convex arcuate traces and upwardly convex arcuate traces are formed. With this machining method, however, the depths and widths of the grooves may undesirably become nonuniform depending on the inclination of the face.
When forming the traces with the same pitch as the pitch (usually 2.8 mm to 3.6 mm) of the corrugations, as in U.S. Pat. No. 5,437,088, the amount of spin does not increase very much.